RS232 and RS485 networking – no code required

Here’s a serial to Ethernet module that you won’t have to write firmware to build. It uses a Lantronix XPORT module which takes care of all the work for you, including an embedded webserver. Both RS232 and RS485 data buses are connected to the XPORT serial input via a level converter to step the signal down to 3.3V. This solution comes at a price because of the ethernet module, but it would make a nice prototyping tool for testing projects that work on the two serial protocols.

I used one of these in my robotics creation in 2004, and the price hasn’t gone down a single cent. I guess they are ripe for a bit of healthy competition.
They have a wireless equivalent: the Wiport, which can triple most of our hobby BOM costs.

Looks like the XPort alone is USD$50. Considering the limited functionality needed for most embedded ethernet devices (raw sockets, web pings anybody?) it might be a pain to deal with the ENC28J60 but at $40 less per unit I’ll keep doing it.

There are cheaper ways of doing the same thing the Xport does, but none as small or simple to connect to. I am not sure why they did not use the Xport which has 5V tolerant IO, or just use 232 and 485 drivers that are 3.3V compatible, it would have saved a lot of level translation. This type of device can be very useful on the work bench.

Having spent the past few weeks working with XPorts for work here are some things to keep in mind about the lowest/cheapest module (I.e. These notes don’t apply to the XPort AR or XPort Pro):
– It has 5V tolerant pins.
– The built-in web server can only serve static data.
– It’s extremely expensive compared to other ethernet modules but it is considerably smaller and fully self-contained.
– It can only handle a single connection at a time on the single forwarded port. If you’re running a webserver on an AVR/PIC behind the XPort for example (For being able to serve dynamic data) there is no way for you to identify unique connections. This means if the user rapidly presses the refresh button in their browser or if they disconnect and someone else connects immediately they will get the wrong data from the device.

Overall the XPort is only suited for simple projects that communicate over RS232/RS485 (Exactly what the XPort is advertised as). If you want to network-enable a serious embedded device consider the XPort Pro (Embedded Linux OS) for small runs or a dedicated ethernet controller IC/microcontroller for larger ones.

@ Franklyn – I have used both the Lantronix and the Han Run products and, believe me when I say you WANT to stay with Lantronix. The Han Run modules are very unreliable. The Lantronix units are great as long as you make sure your power is steady enough that you don’t drop below 2.6V.